Description
Return p at x zero, otherwise the diffusion ratio (1-exp(-xp))/(1-exp(-x)), using stable sign-specific exponential forms.
Population-genetic probabilities depend on copy counts, ploidy, effective size and model assumptions. A neutral fixation identity and a selected diffusion approximation describe different conditions; neither guarantees an actual evolutionary outcome.
Return p at x zero, otherwise the diffusion ratio (1-exp(-xp))/(1-exp(-x)), using stable sign-specific exponential forms.
When to use this tool
Use Adaptation Fixation Supplied Effect Term when you need the stated population-count, coalescent or fixation-model term.
How to use the tool and how it works
- Enter p, effectiveDiploids, selectionCoefficient. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read fixationProbability. Use the output convention below.
Require p in [0, 1], positive effective diploids and finite x=4Ns. Return p at x zero, otherwise the diffusion ratio (1-exp(-xp))/(1-exp(-x)), using stable sign-specific exponential forms.1
The supplied genic-selection diffusion convention uses the ratio [1-exp(-4Ne·s·p)]/[1-exp(-4Ne·s)], with neutral limit p. General dominance or demographic models require other treatments.2
| Input field | Meaning and units | Accepted input |
|---|---|---|
| p | P | Required. Finite number; minimum 0; maximum 1. |
| effectiveDiploids | Effective Diploids | Required. Finite number; strictly above 0. |
| selectionCoefficient | Signed genic selection parameter s under the 4Ne·s diffusion convention. | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| fixationProbability | Fixation Probability | Required. Finite number. |
{
"input": {
"p": 0.1,
"effectiveDiploids": 100,
"selectionCoefficient": 0
},
"output": {
"fixationProbability": 0.1
}
}Limitations and assumptions
- This is a supplied genic-selection diffusion model with its effective-population convention, not a universal selected-allele fixation probability or a prediction of actual adaptation.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use the appropriate population-genetic analysis and data to estimate effective size, selection and uncertainty. Keep actual census counts, effective population conventions and discrete versus continuous-time approximations distinct.
References
Similar or alternative tools
- Fixation Probability Neutral Copy Term
Return copy frequency as neutral fixationProbability.
- Coalescent Two Lineage Rate Term
Return rate 1/(2N), mean time 2N and survival exp(-elapsed/(2N)).